Small animal PET studies are crucial in development of new pharmaceuticals and therapies as well as quantification of diverse biochemical and physiological processes in living organism. Visualized and quantified imaging of structures in small animals, however, imposes stringent requirements on the imaging system. Satisfying these requirements simultaneously necessitates expensive approaches and typically results in trading off between key performance metrics such as spatial resolution and sensitivity. The scintillators used in the majority of the modern PET systems and those under development are high density orthosilicate-based materials such as LYSO, LSO, LGSO, and GSO thanks to their high stopping power, fast decay time, non- hygroscopic nature, and relatively high light output. These scintillators are mechanically pixelated to form an array of scintillator elements to achieve high spatial resolution. However, array fabrication with pixels that have small cross-section (e.g. 1x1 mm2) and large thickness (e.g. 15 mm) is challenging and expensive which leads to a number of issues such as light collection problem, practical difficulties of accurate and consistent crystal size, and high cost associated with fine crystal cutting and surface treatment (polishing). In the mechanically pixelated arrays, a reflecting material is inserted between the pixels which leads to low packing fraction and thereby loss of sensitivity to gamma rays. Our goal is develop a PET detector using recently emerged technology called Laser-Induced Optical barriers (LIOB) in that we create optical barriers within the scintillation detector to control the light spread function and hence the spatial resolution. The significance of this research work is that using LIOB, development of high sensitivity PET detectors with sub-millimeter intrinsic spatial and DOI capability is achievable in a very cost effective manner. Our specific aims are to 1) Simulate the properties of laser induced optical barriers and correlate the results with experimental data. 2) Model a laser processed detector and optimize the optical barriers pattern, and 3) Fabricate and characterize LYSO detectors processed by LIOB technique.